Experimental and simulated investigations of the performance of the solar greenhouse dryer for drying cassumunar ginger (Zingiber cassumunar Roxb.)

This paper presents experimental performance of the greenhouse solar dryer for drying of cassumunar ginger (Plai). The dryer consists of a parabolic roof structure covered with polycarbonate plates on a concrete floor. The base of the dryer is a concrete floor with an area of 9 x 12.4 m(2). Nine DC fans powered by three 50-W PV module were used to ventilate the dryer. The dryer was installed at Sa Kaeo province (13.49 degrees N, 102.21 degrees E), east of Thailand. To investigate the experimental performances, 300 kg of cassumunar ginger was dried in the solar greenhouse dryer. The drying air temperature varied from 30 degrees C to 55 degrees C during drying. The drying time in the solar greenhouse dryer was 1 day to dry cassumunar ginger from an initial moisture content of 90% (wb) to a final moisture content of 10% (wb), whereas it required 1 day of natural sun drying under similar conditions to reach a moisture content of 40% (wb). A system of partial differential equations describing heat and moisture transfer during drying of cassumunar ginger in the solar greenhouse dryer was developed and solved numerically using the finite difference method. Good agreement was found between experimental and simulated moisture contents.